Simple really. A normal games has a captive audience of about 30 minutes. A ranked game lasts for around the same time, the difference being that toxic/trolling players negatively impact your future game thus, keeping you captive of their abuse for much longer.
I can see what your trying to promote, increasing the punishment in ranked games would allow players who actually play the game to allow ranked to be less of an issue. But of course this can be only said in theory. But in the end its really a psychological factor that either makes a player troll or be serious in playing the game. This will never change whatsoever unless Riot decides to mandate very harsh rules like you say in which would not be beneficial in regards to popularity of League of Legends as the community would dissolve and you'd just probably have the dedicated gamers stay to play. It's really the statistics one would have to worry about when such rulings would occur.
I'm all for stricter punishment, but it has to be done verrrrry carefully so as not to wreck the community or be open to abuse.
The bigger problem IMO is the lack of utility of the ignore button. You can 'ignore' someone who's being an idiot or troll or abusive or whatever, but then the very next game you get stuck with them again, so what's the point of ignoring them? I really think that if you add someone to your ignore list, it should remove them from your pool of possible teammates.
I know there's potential for abuse of this in higher ranks (where people team up against one person and everyone ignores them, effectively making that person have nobody to play with), so it could possibly be implemented for only the lower ranks like bronze, silver, and maybe gold.
I think this would go a long way toward weeding out trolls and toxic players from the lower ranks. If you behave badly, not only do you get a short-term punishment, but if people ignore you, the pool of players you can be teamed with shrinks over time.
This would also alleviate the extreme frustration of players who are honestly trying to work their way out of bronze, who lose LP for dodging a game where they're matched with a known troll or toxic player. That is one of my biggest pet peeves about League of Legends: being punished for avoiding trolls and toxic players.
